Wound dressings comprising a backing layer and a layer of hydrocolloid adhesive are well known, such dressings may be known as hydrocolloid dressings. Whereas these dressings are excellent for application to blisters or slowly exuding wounds, they may be difficult to attach to fast exuding wounds, such as a bleeding wound or scratch. Hydrocolloid adhesive is capable of absorbing large amounts of moisture, but not instantaneously as their initial absorption is low.
Typically, the hydrocolloid dressings have a continuous surface against the skin or wound which does not absorb liquid instantaneously. This leads to the issue of small drops of fluid being squeezed across the surface of the dressing during application of the dressing to the wound and this fluid may be squeezed all the way to the edge of the dressing leading to poor adhesion and premature detachment.
There have been different attempts to solve this problem:
One approach is to optimize the adhesive to a faster initial absorption, e.g. by increasing the amount of hydrocolloid. However, the increase in hydrocolloid may lead to a decrease in adhesive tack and thereby a shorter wear time for the wound dressing. Thus, the increase in absorption rate required to deal with the fluid production rate is not compatible with a well adhering hydrocolloid dressing.
Another way is to provide the wound dressing with an absorbent center zone, such as a pad of an absorbent material, such as a gauze or foam or cellulosic material. This will add an extra step in the production and the resulting product may be more visible and less flexible. Furthermore, adding an absorbent pad fundamentally changes the nature of the hydrocolloid dressing as the benefits of having the hydrocolloid adhesive over the wound bed will not be present anymore.
A third way may be to increase the permeability of the dressing, e.g. by providing adhesive-free zones, by pattern coating the adhesive layer to the backing layer. The pattern may be in the form of a dot-shaped pattern coated on backing film allowing increased vapor permeability at the uncoated areas. However, water infiltration or leakage is possible via the interconnected uncoated areas or channels, which are defined between the discrete dots of adhesive.
EP 806 210 discloses an adhesive wafer, in which the adhesive layer of the wafer is composed of a hydrocolloid-containing skin barrier material. The adhesive layer is embossed to provide a pattern of discrete, non-connecting depressions separated and isolated from each other. The structure facilitates less skin stripping during multiple replacements of the wafer as well as the non-connected structure of depressions reduces the risk of leakage.